Metal Fabrication And Application Of Surface Enhanced Infrared Materials

The infrared absorption of sample molecule on certain nanostructure metal surface is enhanced by1or2order of magnitude. This phenomenon is called surface enhance infrared absorption effect(SEIRA). Due to their shape, size of the metal nanoparticles influence on SEIRA effect, the synthesis of nanoparticles with controlled size and morphology has been the core for modern nanotechnology in recent years. In optical electronics fields, noble metal nanoparticJes, such as Au and Ag nanoparticles, are the most intensively studied subject for their unique stability properties and potential applications. However noble metals are expensive, so Cu is often used as alternative candidate to prepare nanoparticles. In this paper, Surface Enhanced IR Active Cu Nanoparticles was prepared. The surface enhanced infrared absorption (SEIRA) effect of the Cu nanoparticles were measured in attenuated total reflection spectroscopy (ATR-FTIR) and transmittance spectroscopy (TR-FTIR) using dimercaptosuccinic acid as the probe. The nanostructure of the copper surface was characterized by scanning electron microscopy (SEM).The infrared surface enhancement mechanism of Active Cu Nanoparticles has been studied. Also the stability of the copper nanoparticles SEIRA has been investigated. In the end, the substrates were applied in biochemistry detection.1. The copper nanoparticles on indium tin oxid (ITO) conductive glass and Ge were prepared by the electrodeposition and chemicaldeposition respectively. The surface enhanced infrared absorption (SEIRA) effect of the Cu nanoparticles were measured in attenuated total reflection spectroscopy (ATR-FTIR) and transmittance spectroscopy (TR-FTIR) using dimercaptosuccinic acid as the probe. The influencing factors on SEIRAS have been investigated in preparing nanoparticles. The law of preparing controllable morphology of nano-copper film was explord. The optimized conditions for preparing copper nanoparticles by electrodeposition were as follows: CuSO4concentration was10-1mol/L,7.2mL diethanolamine as surfactant was added in CuSO4solution, potential was2v, deposition time was30s, and the pH was6.53. The optimized conditions for preparing copper nanoparticles by chemicaldeposition were as follows:CuSO4concentration was10-3mol/L, triethanolamine as surfactant was added in CuSO4solution,deposition time was8h.2. O-nitranline and Dimercaptosuccinic acid were used as probe molecules. Comparing of the conventional infrared spectra and SEIRA spectrum, it is found that O-nitranline adsorbed on substrate prepared by electrodeposition have enhancement effect and the infrared spectra peak did not shift, after cleaning with ethanol, the signal of probe molecules was dispeare. We deduced that its main reasons were the electromagnetic field effect and the physical adsorption. When O-nitranline adsorbed on substrate prepared by chemicaldeposition, signal was not observed. Dimercaptosuccinic acid adsorded on substrate prepared by electrodeposition and chemicaldeposition have enhancement effect, but the peaks of infrared spectra shift. After cleaned with ethanol, the signal of probe molecules was also observed, so we concluded that the main reasons for its enhancement were the elctromagnetic field effect and chemical adsorption.The morphology of the Cu nanoparticles were characterized by scanning electron microscopy, results showed that:adding surfactant(triethanolamine, diethanolamine) in the electrolyte and by adjusting the pH of the electrolyte can prepared controllable morphology of copper nanoparticles. Copper nanoparticles are spherical in shape when the pH value is near neutral and slightly alkaline and the shape is also spherical when the pH value is increased to9-10. Some of the nanoparticles balls start to agglomerate at pH value of6.80. As the pH value continues to decrease, the copper nanoparticles are further stacked and the shape is changed from sphere to block. Finally, the shape turns to dendritic at pH value of3.13. Experiments showed that the O-nitroaniline was not obtain enhancemen effect on various copper nanoparticles, only on substrate prepared by using diethanolamine as surfactant, pH of6.53have the best enhanced effect, its distribution was more dispersion, particle size about300nm. Using Dimercaptosuccinic acid as probe molecule to investigate the enhancement effect of copper nanoparticles prepared by chemicaldeposition. The results show that: incident angle of the incident light affect the SEIRA of substrate, so for attenuated total reflection detection and the transmission detection the SEIRA material have different morphology and thickness. In this experiment, the copper nanoparticles size about100nm and500nm prepared by chemicaldeposition respectively used in AIR and transmission detection.3. Infrared attenuated total reflection method (ATR-FTIR) and spectral subtraction was applied in analyzing Bovine serum albumin in different environment, the results show that ATR-FTIR was a very convenient method for analyzing biological proteins. The copper nanoparticles were prepared by chemicaldeposition as substrate to detect different concentrations of the protein solution and cancer cell, the results showed that the infrared absorption of adsorbed molecules on active Cu nanoparticles substrate was enhanced, but if there is chemiscal interaction between adsorbed molecules and substrate, it is not suitable for structural analysis.